1. Field of the Invention
The present invention relates generally to packaging semiconductor dice to produce integrated circuits. It particularly relates to packaging a semiconductor die that enables greater heat dissipation and build-up layer fabrication efficiency.
2. Background
Higher performance, lower cost, increased miniaturization of integrated circuit components and greater packaging density of integrated circuits are ongoing goals of the computer industry. As these goals are achieved, semiconductor dice become smaller. Of course, the goal of greater packaging density requires that the entire semiconductor die package be equal to or only slightly larger (about 10% to 30%) than the size of the semiconductor die itself. Such semiconductor die packaging is called a “chip scale packaging” or “CSP”.
Generally, for most CSP, the surface area provided by the active surface for most semiconductor dice does not provide enough surface for all of the external contacts needed to contact external devices for certain types of semiconductor dice. Additional surface area can be provided with the use of an interposer, such as a substantially rigid material or a substantially flexible material. FIG. 16 illustrates a substrate interposer 222 having a semiconductor die 224 attached to and in electrical contact with a first surface 226 of the substrate interposer 222 through solder balls 228. The solder balls 228 extend between contacts 232 on the semiconductor die 224 and conductive traces 234 on the substrate interposer first surface 226. The conductive traces 234 are in discrete electrical contact with bond pads 236 on a second surface 238 of the substrate interposer 222 through vias 242 that extend through the substrate interposer 222. External contacts 244 are formed on bond pads 236. The external contacts 244 are utilized to achieve electrical communication between the semiconductor die 224 and an external electrical system (not shown).
The use of the substrate interposer 222 requires a number of processing steps which increase the cost of the package. Additionally, the use of the small solder balls 228 presents crowding problems which can result in shorting between the small solder balls 228 and can present difficulties in inserting underfill material between the semiconductor die 224 and the substrate interposer 222 to prevent contamination and provide mechanical stability. Furthermore, the necessity of having two sets of solder balls (i.e., small solder balls 228 and external contacts 244) to achieve connection between the semiconductor die 224 and the external electrical system decreases the overall performance of the package.
Another problem arising from the fabrication of a smaller semiconductor die is that the density of power consumption of the integrated circuit components in the semiconductor die has increased, which, in turn, increases the average junction temperature of the die. If the temperature of the semiconductor die becomes too high, the integrated circuits of the semiconductor die may be damaged or destroyed. Furthermore, for semiconductor dice of equivalent size, the overall power increases which presents the same problem of increased power density.
Various apparatus and techniques have been used for removing heat from semiconductor dice. Some techniques involve the use of encapsulation materials to encapsulate semiconductor dice on to a heat spreader, or to embed (secure) semiconductor dice into recesses (cavities) within a heat spreader for heat dissipation. The use of these techniques produces additional, complicated processing steps for fabricating an integrated circuit package. Therefore, it would be advantageous to develop new apparatus and techniques for integrated circuit fabrication that eliminate complicated processing steps and the necessity of the substrate interposer, and provides improved heat dissipation.